A client with an indwelling urinary catheter is suspected of having a urinary tract infection. The nurse should collect a urine specimen for culture and sensitivity by（）

A. disconnecting the tubing from the urinary catheter and letting the urine flow into a sterile container.

B. wiping the self-sealing aspiration port with antiseptic solution and aspirating urine with a sterile needle.

C. draining urine from the drainage bag into a sterile container.

D. clamping the tubing for 60 minutes and inserting a sterile needle into the tubing above the clamp to aspirate urine.

一盏台灯正常工作时的电流为200毫安，合______安，通电600秒，通过灯丝横截面的电量为______库．